The proposed work centers on proteins from a line of cultured hepatoma cells (HTC cells). In particular we are interested in nonhistone chromatin proteins that exhibit preferential affinity for single-stranded DNA. We have previously isolated two HTC cell NHCP's that have this characteristic, using sequential chromatography on double-stranded and single-stranded DNA columns. The two proteins are tumor-enriched in the sense that they occur in much higher amounts in HTC cells than in normal adult rat liver. We have also found that the proteins occur in the cytoplasm of HTC cells. In the coming project year, we intend to investigate whether the cytoplasmic and nuclear forms of the proteins are identical and whether the proteins can act as helix destabilizers. We will also examine the amounts of the proteins that occur in HTC cells that are proliferating at widely different rates.